[Amps] Noisy Power Transformer

[Jim Brown]

I've just acquired a vintage Titan 425. After fixing some problems, 
I think I may have it running OK, except that the power transformer 
is making a lot more noise on keydown than my two other Titan p/s. 
Is this a symptom of a likely failure mode, or only a nuisance? How 
loud is it?  Loud enough that it's unpleasant when I'm working CW 
with headphones that have fairly good isolation, but bearable if I'm 
working SSB (to the extent that SSB is bearable). :)

73,

Jim K9YC